Generally, barbecue grills include an oven-like housing for cooking food on a grilling surface. A heat source, such as burning charcoal or a gas flame radiates heat from beneath the grilling surface directly to the food lying on the grilling surface. A cover over the grilling surface retains heat produced by the heat source. The cover also traps smoke and steam that enhance the flavor of the food being cooked.
Some covers include a window that allows the cook to monitor the cooking of the food. However, smoke often clouds the window and prevents the cook from visually inspecting the food. Thus, even with the window the cook may sometimes need to open the cover just to check the cooking process.
The cover provides convenient access to the cooking food, but fully opening the cover allows heat and smoke to escape from the grill. Opening and closing the cover also affects the flow of oxygen within the grill. The rate of combustion for a fuel source depends in part on the amount of oxygen available. The combustion rate in turn affects the grill temperature. A low oxygen level within the grill may also reduce or eliminate fat-fueled fires. The cover is therefore a useful component of a barbecue grill.
Some barbecue grills do not have a cover, and others provide a cover that is removable. However, there is a need for a barbecue grill that allows a cook to control the size of the opening between the grill and the cover. It is therefore desirable to provide a grill having a cover with an adjustable opening to control oxygen circulation and retain heat and smoke.
Barbecue grills that use a combustible fuel source such as charcoal briquettes do not always provide a constant source of heat. When the briquettes are first ignited, very little heat is produced. After the briquettes become fully ignited, a peak temperature is reached. The temperature then gradually declines as the fuel is consumed. The size of the opening between the cover and the grilling surface affects the temperature on the grill, and it is therefore desirable to adjust the cover opening throughout the cooking process.